Operation of electrical devices, such as high-power semiconductor devices, high-power lasers, microprocessors and/or light emitting diodes (LEDs), is often associated with generation of heat. The heat is a byproduct that may have an injurious effect on performance and lifetime of the electrical device. Effective cooling is therefore useful and desired in many applications. For cooling of electrical devices which may generate heat when in use, or when operated, heat sinks which either employ free convection or forced convection are often used. Heat sinks based on free convention may however have some disadvantages. The heat transfer rate by way of convection and thermal radiation may be relatively low, and thereby passive heats sinks may be heavy and/or voluminous. Further, the cooling efficiency of such a heat sink may depend on its particular spatial orientation. Heat sinks based on forced convection, i.e. heat sinks which are used in conjunction with a fan, generally do not suffer from the above-mentioned drawbacks of heat sinks based on free convection. However, heat sinks based on forced convection may have other disadvantages. While the cooling efficiency of heat sinks based on forced convection is generally higher compared to that of heat sinks based on free convention, heat sinks based on forced convection generally require more installation space for accommodating the fan(s) and for example inlet(s) and outlet(s) for the fan(s). The fan may produce a relatively high level of noise. The fan may have a relatively limited lifetime, and may need to be replaced at relatively frequent intervals.
In view of the above discussion, a concern of the present invention is to provide a cooling arrangement for cooling of an apparatus which in use may generate heat, which addresses at least the above-discussed disadvantages with heat sinks based on forced convection.
To address at least one of this concern and other concerns, a cooling arrangement in accordance with the independent claim is provided. Preferred embodiments are defined by the dependent claims.
The cooling arrangement utilizes a construction for generating a flow of fluid to which any heat that is generated may be transferred, which construction may operate similarly to a so called scroll compressor. A scroll compressor is compressor type in which two so called scrolls perform a relative orbiting motion, and where substantially symmetrical compression chambers for fluid such as a gas are formed between the two scrolls. The scrolls are constituted by spiral-shaped fins. In a scroll compressor there is usually a stationary scroll part having an exhaust opening at the center thereof, and a movable scroll part, which may be referred to as the orbiter, which is driven by an electrical motor. By the relative orbiting motion of the two scrolls, a volume of the compression chamber is progressively decreasing as the compression chamber moves toward the center of the scroll, compressing the gas held in the compression chamber, and thereby transporting the gas towards the center of the scroll where it can exit at the exhaust opening. The scroll compressor can thereby be used to generate a flow of the gas (or any other fluid). The orbiting motion of the orbiter with respect to the stationary scroll part can be generated by means of an eccentric mechanical part which is connecting the motor axis with the orbiter axis. The orbiter may hence be mounted eccentrically on the motor axis. The cooling arrangement may utilize such a drive unit, or drive system. In alternative or in addition the cooling arrangement may utilize an electromagnetic and/or electromechanical actuator based drive unit, as will be further described in the following.
According to a first aspect of the present invention there is provided a cooling arrangement for cooling of an apparatus which when used may generate heat. The cooling arrangement comprises a first member and a second member. The first member comprises a first base and a first spiral wrap, or first spiral fin, extending from the first base. The second member comprises a second base and a second spiral wrap, or second spiral fin, extending from the second base. The first spiral wrap and the second spiral wrap are interleaved, or interfitted. The first member is configured to at least thermally couple the apparatus thereto. At least one of the first member and the second member can be (possibly controllably) moved (possibly by means of the first member and the second member being configured or arranged appropriately) so as to result in an orbiting motion of one of the first spiral wrap and the second spiral wrap relatively to the other one of the first spiral wrap and the second spiral wrap, such that a volume of fluid in at least one space between the first spiral wrap and the second spiral wrap progressively moves during the orbiting motion, thereby generating a flow of fluid between the first spiral wrap and the second spiral. The flow of fluid may cool at least the first member by means of dissipation of heat generated by the apparatus by way of transfer of heat from the first member to the flow of fluid between the first spiral wrap and the second spiral.
By way of the first spiral wrap and the second spiral wrap of the first member and the second member, respectively, being interleaved, or interfitted, and by the at least one of the first member and the second member being movable so as to result in the above-mentioned orbiting motion such that a volume of fluid in at least one space between the first spiral wrap and the second spiral wrap progressively moves during the orbiting motion, the cooling arrangement may operate similarly to a so called scroll compressor (but possibly with only little or without compression of the fluid between the first spiral wrap and the second spiral wrap). The cooling arrangement can thereby be used to generate a flow of fluid such as a gas, e.g., air.
By the at least one of the first member and the second member being movable so as to result in the above-mentioned orbiting motion such that a volume of fluid in at least one space between the first spiral wrap and the second spiral wrap progressively moves during the orbiting motion, it is meant that at least one fluid ‘pocket’ between the first spiral wrap and the second spiral wrap is progressively or consecutively moved or displaced during the orbiting motion.
The at least one of the first member and the second member may be movable so as to result in the above-mentioned orbiting motion such that a volume of fluid, or fluid pocket, in at least one space between the first spiral wrap and the second spiral wrap progressively moves during the orbiting motion for example towards a center of at least one of the first member and the second member, where an exhaust or outlet may be arranged.
As mentioned in the foregoing, the first member is configured to at least thermally couple the apparatus thereto. By means of the flow of fluid generated between the first spiral wrap and the second spiral wrap, and hence between the first member and the second member, heat generated by the apparatus may be dissipated by way of transfer of heat from the first member to the flow of fluid between the first spiral wrap and the second spiral. Thus, the cooling arrangement provides for a heat sink solution based on forced convection (and which may be referred to as an active heat sink), which may operate similarly to a so called scroll compressor. In contrast to most heat sinks based on forced convention, the cooling arrangement does not require a fan for creating a fluid flow. Rather, the means of creating the fluid flow in the cooling arrangement, i.e. the first member and the second member, are constituted in part by the heat sink itself, i.e. the first member, which is configured to at least thermally couple the apparatus thereto. Thereby, the cooling arrangement may require less installation space compared to most other heat sinks based on forced convention.
A cooling arrangement according to the first aspect may for example be employed for cooling of electronic equipment, such as cooling of lighting devices based on light-emitting diodes, such as downlights, spot luminaires, etc.
In alternative or in addition, the second member may be configured to at least thermally couple the apparatus thereto (possibly instead of the first member).
The cooling arrangement may be used for cooling of several apparatuses which in use may generate heat. The first member may be configured to at least thermally couple at least one of the apparatuses thereto, and the second member may be configured to at least thermally couple at least one (other) of the apparatuses thereto.
In the context of the present application, by spiral it is meant a curve on a plane that winds around a central point at a continuously increasing or decreasing distance from the central point. Thus, each of the first spiral wrap and the second spiral wrap represents a structure having walls which similarly to a spiral revolves around a central point, as seen from above the first and second base, respectively. The spacing between different turns of the first spiral wrap and/or the second spiral wrap may be the same, or it may differ at least between some turns.
In the context of the present application, by the first spiral wrap and the second spiral wrap being interleaved, or interfitted, it is meant that they are arranged in or as if in alternate layers.
Each of the first spiral wrap and the second spiral wrap may for example have an involute (or evolvent) geometry or shape. That is to say, the walls of each of the first spiral wrap and the second spiral wrap may, when seen from the above (of the first member and second member, respectively), exhibit a shape similar to an involute or evolvent curve. However, other geometries or shapes of the first spiral wrap and/or the second spiral wrap are possible.
At least one of the first member and the second member may be moved so as to result in an orbiting motion of one of the first spiral wrap and the second spiral wrap relatively to the other one of the first spiral wrap and the second spiral wrap such that one of the first spiral wrap and the second spiral wrap is driven to orbit eccentrically relatively to the other one of the first spiral wrap and the second spiral wrap.
According to one or more embodiments of the present invention, both the first member and the second member are movable, and possibly both of them are moved so as to result in the orbiting motion of one of the first spiral wrap and the second spiral wrap relatively to the other one of the first spiral wrap. In alternative, one of the first member and the second member may be movable with the other one being fixedly arranged (in the apparatus). For example, first member may be fixedly arranged (in the cooling arrangement) and the second member may be movable relatively to the first member. The second member may be controllably moved with respect to the first member so as to result in an orbiting motion of the second spiral wrap relatively to the first spiral wrap, possibly such that the second spiral wrap is driven to orbit eccentrically relatively to the first spiral wrap. Thus, the first member and the second member may be arranged such that the second spiral wrap can be driven to orbit eccentrically relatively to the first spiral wrap.
In the context of the present application, by one spiral wrap being driven to orbit eccentrically relatively to another spiral wrap it is meant that one spiral wrap is orbiting around an axis that is different from the center axis of the other spiral wrap.
The orbiting motion of one of the first spiral wrap and the second spiral wrap relatively to the other one of the first spiral wrap and the second spiral wrap may be such that the one of the first spiral wrap and the second spiral wrap may at least during part of the orbiting motion possibly is in sliding contact with the other one of the first spiral wrap and the second spiral wrap, so as to minimize radial gap between the spiral wraps. This may possibly improve the pumping efficiency.
The cooling arrangement, or at least one of the first member and the second member, may comprise an inlet, which permits fluid to enter between the first spiral wrap and the second spiral wrap. At least one of the first member and the second member may comprise an outlet for outputting the flow of fluid generated between the first spiral wrap and the second spiral wrap. Thereby, fluid may be conveyed between the inlet and the outlet.
At least one of first spiral wrap and the second spiral wrap may be arranged such that it is wrapped at most 1.5 revolutions about its origin. Thereby, fluid ‘pockets’ between the first spiral wrap and the second spiral wrap will during the orbiting motion never fully be closed off, so as to facilitate or allow for fluid to escape from between the first spiral wrap and the second spiral wrap towards the outlet. Such a configuration may be useful for example in case the cooling arrangement will be used to generate an air flow, or air jet. However, in case one of the first member and the second member is stationary and the other is movable (for example, if the first member is fixedly arranged and the second member is movable relatively to the first member), the stationary member may be arranged such that it is wrapped more than 1.5 revolutions about its origin while still facilitating or allowing for fluid to escape from between the first spiral wrap and the second spiral wrap towards the outlet. In that way, the surface area available for cooling becomes larger.
The cooling arrangement may comprise a heat spreader, which may be coupled to the first member. The first member may be configured to couple the apparatus to the first member via the heat spreader. The heat spreader may for example comprise an intermediate element or component arranged on a surface of the first member, via which intermediate element or component the apparatus may be coupled to the first member, for improving the thermal coupling between the apparatus and the first member. The heat spreader may for example comprise a plate or the like. The heat spreader may for example comprise a material having a relatively high thermal conductivity, such as copper or aluminum. In alternative or in addition the heat spreader may for example comprise thermal interface material (TIM) such as thermal grease.
The cooling arrangement may comprise a drive unit configured to controllably move at least one of the first member and the second member so as to result in the orbiting motion.
The drive unit may for example comprise at least one electromagnetic and/or electromechanical actuator configured to controllably generate forces, e.g., electromagnetic forces, which affect the at least one of the first member and the second member in order to controllably move the at least one of the first member and the second member so as to result in the orbiting motion. The cooling arrangement may hence utilize an electromagnetic and/or electromechanical actuator based drive unit for moving at least one of the first member and the second member. For example, by means of such a drive unit, less or no bearings may be required in order to operate the cooling arrangement, and therefore no or only little noise may be generated during operation of the cooling arrangement, and there may be less need for replacing worn-out part of the cooling arrangement (bearings may become worn out relatively quickly), as compared to a drive system having a motor with the orbiter being mounted eccentrically on the motor axis.
The at least one electromagnetic and/or electromechanical actuator may for example be a linear actuator. The at least one electromagnetic and/or electromechanical actuator may for example be configured to controllably generate forces which affect the at least one of the first member and the second member in order to controllably move the at least one of the first member and the second member in motions along different straight axes so as to result in the orbiting motion. The at least one electromagnetic and/or electromechanical actuator may hence, according to one or more embodiments of the present invention, be referred to as a ‘linear’ actuator.
The at least one electromagnetic and/or electromechanical actuator of the drive unit may for example comprise a static wire coil, which when energized may create a magnetic field. The first member and/or the second member, or some other element(s) which may be coupled to and/or supporting the first member and/or the second member, may when exposed to the magnetic field be attracted to or repelled by the static wire coil, thereby effecting movement (possibly controllable) of the first member and/or the second member. The at least one electromagnetic and/or electromechanical actuator may for example operate similarly to a solenoid or a linear electromagnetic motor, both of which as such are known in the art.
In alternative or in addition the electromagnetic and/or electromechanical actuator may for example comprise a piezoelectric actuator, which for example may utilize one or more piezoelectric crystals or materials, which may change at least one dimension thereof when an external electric field is applied to the piezoelectric crystal(s) or material(s). Thereby, the electromagnetic and/or electromechanical actuator may be configured to produce a force responsive to application of an external electric field.
It is to be understood that the above-described types of electromagnetic and/or electromechanical actuators are according to non-limiting examples, and that the drive unit may employ another or other types of electromagnetic and/or electromechanical actuators.
The at least one electromagnetic and/or electromechanical actuator may be configured to controllably generate forces, e.g., electromagnetic forces, which (directly or indirectly) may affect the at least one of the first member and the second member in order to controllably move the at least one of the first member and the second member along at least two mutually perpendicular imaginary axes in respective oscillatory motions, resulting in the orbiting motion of one of the first spiral wrap and the second spiral wrap relatively to the other one of the first spiral wrap and the second spiral wrap. The at least one electromagnetic and/or electromechanical actuator may be configured to controllably generate forces which affect the at least one of the first member and the second member in order to controllably move the at least one of the first member and the second member along at least two mutually perpendicular imaginary axes in respective oscillatory motions having controllable amplitude and/or controllable phase. The above-mentioned orbiting motion may for example be generated by way of two mutually perpendicular, or orthogonal, mechanical oscillatory movements by the first member and the second member, respectively, which respective oscillatory movements may have a phase difference of 90° (π/2 radians), or about 90° (e.g., the oscillations being phase-shifted relatively to each other), and possibly have the same (or substantially the same) amplitude. The respective oscillatory movements may for example have an oscillation frequency between about 20 Hz and about 50 Hz.
As mentioned in the foregoing, the forces may directly affect the at least one of the first member and the second member in order to controllably move the at least one of the first member and the second member so as to result in the orbiting motion. For example, at least a portion of the at least one of the first member and the second member may be magnetic. The at least one electromagnetic and/or electromechanical actuator may be configured to controllably apply forces onto at least a portion of at least one of the first member and the second member (in order to controllably move the at least one of the first member and the second member so as to result in the orbiting motion).
In alternative or in addition, the forces may indirectly affect the at least one of the first member and the second member in order to controllably move the at least one of the first member and the second member so as to result in the orbiting motion. The cooling arrangement may for example comprise a support structure (or suspension), wherein at least a portion of the support structure is configured to resiliently support (or suspend) at least one of the first member and the second member in the cooling arrangement while permitting movement of the at least one of the first member and the second member resulting in the orbiting motion. For example, at least a portion of the support structure may be magnetic. The at least one electromagnetic and/or electromechanical actuator may be configured to controllably apply forces onto at least a portion of the support structure in order to controllably move the at least one of the first member and the second member so as to result in the orbiting motion. The movement of the at least one of the first member and the second member may be effected by way of the resilient supporting of the at least one of the first member and the second member by the support structure. According to another example the at least one electromagnetic and/or electromechanical actuator may comprise one or more piezoelectric crystals or elements, which may be (possibly directly) arranged on or mounted to at least a portion of the support structure, for controllably generating forces which affect at least one of the first member and the second member in order to controllably move the at least one of the first member and the second member so as to result in the orbiting motion.
The first member may be configured to couple the apparatus thereto. That is to say, the first member may be configured to mechanically (and not only thermally) couple the apparatus thereto.
The first base may comprise a first side and a second side. The first spiral wrap may for example extend from the first side. The first member may be configured to couple the apparatus to the second side. The second side of the first base may for example be opposite to the first side of the first base.
According to a second aspect there is provided a system which comprises an apparatus, which when used may generate heat. The system further comprises a cooling arrangement according to the first aspect for dissipating heat generated by the apparatus when it is used. The cooling arrangement is at least thermally coupled to the first member of the apparatus. The cooling arrangement may be comprised in the apparatus.
The apparatus may for example comprise a light-emitting device configured to emit light when in use. However, it is to be understood that this is according to a non-limiting example, and the apparatus may comprise in principle any apparatus that may generate heat when used, such as, for example, an electrical apparatus.
The light emitting device may for example comprise a carrier substrate, such as, for example, a printed circuit board, on which one or more light-emitting diodes (LEDs) may be arranged. The carrier substrate may possibly be coupled or connected to the second side of the first member. The carrier substrate may for example comprise a printed circuit board, which may be flexible, or substantially rigid, e.g., including a metal core printed circuit board. In alternative or in addition the carrier substrate may comprise a flexible foil. In alternative or in addition, the light emitting device may comprise one or more other types of solid state light emitter other than LED.
Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments. It is noted that the present invention relates to all possible combinations of features recited in the claims. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the description herein. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described herein.
All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate embodiments of the present invention, wherein other parts may be omitted or merely suggested.